Effect of barley straw biochar application on greenhouse gas emissions from upland soil for Chinese cabbage cultivation in short-term laboratory experiments   总被引：1，自引：0，他引：1  

Se-Won Kang  Dong-Cheol Seo  Yong-Hwa Cheong  Ju-Wang Park  Jong-Hwan Park  Hang-Won Kang  Ki-Do Park  Yong Sik Ok  Ju-Sik Cho 《山地科学学报》2016,13(4):693-702

Chinese cabbage was cultivated in upland soil with the addition of biochar in order to investigate the potential for reduction of greenhouse gas emissions. Barley straw biochar (BSB) was introduced in a Wagner pot (1/5000a) in amounts of 0 (BSB0, control), 100 (BSB100), 300 (BSB300), and 500 (BSB500) kg 10a^-1. After the addition of BSB into the upland soil, carbon dioxide (CO₂) emission increased while methane (CH₄) and nitrous oxide (N₂O) emissions decreased. The highest CO₂ flux was measured for the BSB500 sample, (84.6 g m^-2) followed by BSB300, BSB100, and BSB0 in decreasing order. Relative to those of control, the total CH₄ flux and N₂O flux for the BSB500 treatment were lower by 31.6% and 26.1%, respectively. The global warming potential (GWP) of the treatment without biochar was 281.4 g CO₂ m^-2 and those for treatments with biochar were in the range from 194.1 to 224.9 g CO₂ m^-2. Therefore, introducing BSB into upland soil to cultivate Chinese cabbages can reduce the global warming potential.  相似文献   

Estimation of sand transport by use of tracers along a reclaimed shoreline at Singapore Changi Airport     

Hin-Fatt Cheong  N.Jothi Shankar  R. Radhakrishnan  Ah-Cheong Toh 《Coastal Engineering》1993,19(3-4)

This paper describes a probabilistic approach in the estimation of the sediment transport along the reclaimed shoreline at the Singapore Changi Airport through a detailed analysis of the data obtained from a radio-active tracer experiment conducted on site by the Port of Singapore Authority (PSA).The probabilistic approach showed that the transport rate per unit transverse width of the beach is proportional to the effective depth of transport and the speed of the centroid of the probability function describing the dispersion of the cloud of tracers.  相似文献   

Hydrogeological characteristics of waterlogged areas in Natore District,Bangladesh     

Hassan  Md Mahmudul  Jahan  Chowdhury S.  Cheong  Jae-Yeol  Hamm  Se-Yeong 《Hydrogeology Journal》2023,31(3):557-570

Waterlogging (WL) refers to the process by which water flow is resisted in vertical and horizontal directions and thus water stagnates for a short or long span of time; it is induced by a combination of human and natural factors. In the southwestern region of Bangladesh, including Natore District, WL is a significant issue that needs to be addressed if agricultural activity is to be successful. This study aimed to identify surface WL in Natore District and to characterise the WL scenario in the study area in terms of hydrogeology. Waterlogged areas were identified with a geographic information system using satellite images corresponding to the premonsoon and postmonsoon periods. Using groundwater level data (1990–2017), the pre- and postmonsoon scenarios of the waterlogged areas were indicated by seasonal and perennial types of WL. Groundwater recharge scenarios were classified as long and short lag times. Most of the study area was characterised by thick clay or silty clay surficial layers with low water penetration rates, resulting from low porosity and low hydraulic conductivity. The cross-correlation between rainfall and groundwater level revealed the response of groundwater to rainfall, with a lag time of 1–5 months. Long lag time areas exhibited slow groundwater recharge and significant groundwater level fluctuation, with lower hydraulic conductivity values of 49.37–76.24 m/day. In contrast, short lag time areas displayed rapid groundwater recharge and small groundwater fluctuation due to a good proportional relationship with rainfall and higher hydraulic conductivity values of 74.74–117.79 m/day.

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Paleomagnetic records and mineral-magnetic properties of deep-sea sediments in the NW pacific: Paleoenvironmental implication     

Cheong Kee Park  Wonnyon Kim  Youngtak Ko  Hyun-Bok Lee  Jai-Woon Moon  Seong-Jae Doh 《Ocean Science Journal》2012,47(4):497-508

The paleomagnetic records and mineral-magnetic properties of unconsolidated core sediment from the east Mariana Basin of the western Pacific have been analyzed to trace the time-dependent variations in sedimentary environments. Progressive alternating field demagnetization effectively extracts a stable remanent magnetization showing both normal and reverse polarities. Comparison of successive polarity changes, recorded in the sediment core, with reference magnetic polarity time-scale, reveals that the recovered sediment column was deposited since the late Pliocene. From the sediment age model, calculated sedimentation rate during the late Pliocene was 9.8 times higher than that during the Pleistocene. Considering the oceanic environments and geologic setting in the study area, the anomalous high sediment flux during the late Pliocene was probably caused by enhanced current flows, such as North Equatorial Current, associated with atmospheric circulation as well as by debris flows from adjacent sea mounts. In addition, the systematic variation of mineral-magnetic properties indicates periodical fluxes of coarse and magnetically stable particles, on the fine-grained dominant sedimentary environments. Such influxes, however, would not be related to syn-volcanic activities, because the summits of seamounts were totally blanketed by biogenic Pliocene-Pleistocene sediments. It is, hence, reasonable to interpret that paleomagnetic and mineral-magnetic data probably reflect drastic paleoenvironmental changes at the boundary between the Pliocene and Pleistocene, where strong current and atmospheric circulations decreased.  相似文献   

Geochemical and Sr–Nd isotopic constraints on the petrogenesis of the Goesan monzodiorite pluton in the central Okcheon belt,Korea          下载免费PDF全文

Chang‐Sik Cheong  Hui Je Jo  Youn‐Joong Jeong  Chan‐Soo Park  Moonsup Cho 《Island Arc》2016,25(1):43-54

The Permian–Triassic high pressure metamorphism and potassic magmatism in central Korea attest to the extension of the Dabie‐Sulu collision belt in central‐eastern China towards the Korean Peninsula and possibly the Japanese Islands. We present major and trace element and Sr–Nd isotope data for a ca. 230 Ma monzodiorite pluton emplaced in the Goesan area, central Okcheon belt, Korea. This pluton shows geochemical features comparable with those of the coeval monzonite–syenite–gabbro–mangerite suite documented recently in the Gyeonggi massif. The metaluminous and alkali–calcic signatures of the Goesan intrusives correspond to the Caledonian‐type post‐orogenic granitoids. The K₂O/Na₂O ratios of all analyzed samples are greater than 1, and are not correlative with their SiO₂ contents. The enrichment of both large‐ion‐lithophile elements and highly compatible elements in the Goesan pluton is probably indicative of metasomatized mantle origin. The elemental fractionation in the source region must have occurred in the distant past, possibly the Paleoproterozoic, to generate significantly negative ε_Nd(t) values (< –16). Chondrite‐normalized rare earth element patterns as well as Rb/Sr and Ba/Rb ranges suggest that the source consists of amphibole‐bearing rocks. Progressive decreases in negative Eu anomaly and Ba, Sr, Ni, Cr and V contents with increasing SiO₂ contents reflect an important role of plagioclase, biotite and hornblende for the fractionation process. Zr is undersaturated in the potassic, metaluminous melt. The initial Sr–Nd isotopic compositions of the samples are correlated with their SiO₂ contents, substantiating a role of crustal assimilation during the magmatic differentiation. The Sr–Nd elemental and isotopic modeling suggests that the Goesan pluton was initially slightly heterogeneous in its isotopic composition, and underwent concurrent assimilation and fractional crystallization. The occurrence of the Goesan pluton provides further evidence corroborating the amalgamation of allochthonous terranes within the Okcheon belt during the Permian–Triassic collisional orogeny.  相似文献   

Rock Magnetic Approaches Used on Deep-sea Sediments in the Northeastern Equatorial Pacific     

Cheong Kee Park  Gun Chang Lee 《Ocean Science Journal》2018,53(2):369-380

Rock magnetic properties of unconsolidated sediments from the Korea Deep Ocean Study area of the northeastern equatorial Pacific were analyzed to trace the time-dependent variations of sedimentary environments. For upper Pleistocene sediments, light-brown sediments predominate, whereas the lower sediments deposited in the late Pliocene are dark brown. Rock magnetic properties also clearly differ among the two distinct color environments. Values of anhysteretic remanent magnetization and low-field magnetic susceptibility are highly responsive to changes in the color of the sediment. For example, comparatively low values denote a dominance of coarse-grained magnetic minerals as observed in the lower dark-brown layers. With respect to the content of magnetic minerals, coarse magnetic grains are highly concentrated in the darker-colored sediment layers. However, both the magnetic mineral dependent parameter (S ratio) and results of the scanning electron microscope observation indicate that magnetic mineral changes did not occur along the core depth, which means that there was no apparent source change. Without distinctive source changes, the variations in the rock magnetic properties likely reflect a process by which the magnetic grains were primarily transported by enhanced wind and bottom currents and affected by diagenetic dissolution as a function of both the time from burial and the extremely low sedimentation rates after deposition.  相似文献   

Evaluating the impact of visualization of risk upon emergency route-planning     

Lisa Cheong  Christoph Kinkeldey  Ingrid Burfurd  Susanne Bleisch 《International journal of geographical information science》2020,34(5):1022-1050

ABSTRACT

This paper reports on a controlled experiment evaluating how different cartographic representations of risk affect participants’ performance on a complex spatial decision task: route planning. The specific experimental scenario used is oriented towards emergency route-planning during flood response. The experiment compared six common abstract and metaphorical graphical symbolizations of risk. The results indicate a pattern of less-preferred graphical symbolizations associated with slower responses and lower-risk route choices. One mechanism that might explain these observed relationships would be that more complex and effortful maps promote closer attention paid by participants and lower levels of risk taking. Such user considerations have important implications for the design of maps and mapping interfaces for emergency planning and response. The data also highlights the importance of the ‘right decision, wrong outcome problem’ inherent in decision-making under uncertainty: in individual instances, more risky decisions do not always lead to worse outcomes.  相似文献   

Enabling maps/location searches on mobile devices: constructing a POI database via focused crawling and information extraction     

Hsiu-Min Chuang  Ting-Yao Kao  Chung-Ting Cheng  Ya-Yun Huang  Kuo-Pin Cheong 《International journal of geographical information science》2016,30(7):1405-1425

With the popularity of mobile devices and smartphones, we have witnessed rapid growth in mobile applications and services, especially in location-based services (LBS). According to a mobile marketing survey, maps/location searches are among the most utilized services on smartphones. Points of interest (POIs), such as stores, shops, gas stations, parking lots, and bus stops, are particularly important for maps/location searches. Existing map services such as Google Maps and Wikimapia are constructed manually either professionally or with crowd sourcing. However, manual annotation is costly and limited in current POI search services. With the abundance of information on the Web, many store POIs can be extracted from the Web. In this paper, we focus on automatically constructing a POI database to enable store POI map searches. We propose techniques that are required to construct a POI database, including focused crawling, information extraction, and information retrieval techniques. We first crawl Yellow Page web sites to obtain vocabularies of store names. These vocabularies are then investigated with search engines to obtain sentences containing these store names from search snippets in order to train a store name recognition model. To extract POIs scattered across the Web, we propose a query-based crawler to find address-bearing pages that might be used to extract addresses and store names. We crawled 1.25 million distinct POI pairs scattered across the Web and implemented a POI search service via Apache Lucent’s search platform, called Solr. The experimental results demonstrate that the proposed geographical information retrieval model outperforms Wikimapia and a commercial app called ‘What’s the Number?’  相似文献   

Structure change of Typhoon Nari (2007) in the weakening stage     

In-Hyuk Kwon  Hyeong-Bin Cheong  Hyun-Gyu Kang  Hyun-Jun Han  Ja-Rin Park 《Asia-Pacific Journal of Atmospheric Sciences》2010,46(3):327-340

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Tracking source materials of Phanerozoic granitoids in South Korea by zircon Hf isotopes     

Chang‐sik Cheong  Keewook Yi  Namhoon Kim  Tae‐Ho Lee  Seung Ryeol Lee  Jian‐zhen Geng  Huai‐kun Li 《地学学报》2013,25(3):228-235

Phanerozoic granitoids in South Korea are classified into four primary spatiotemporal groups showing geochemical and isotopic diversity. This study presents the first in situ Hf isotope data for zircons extracted from representative outcrops of each granitoid group. The core‐to‐rim variation in ε_Hf values observed in some zircon grains provides evidence for open‐system processes influenced by the input of more primitive melts or interactions with pre‐existing crustal materials. A general core‐to‐rim decrease in Lu/Hf and Th/U ratios indicates a progressive compositional change in the melts during magmatic differentiation. Contrasting evolutionary paths demonstrated by zircon ε_Hf values suggest that the Neoproterozoic to Palaeozoic crust including the Permian granitoids was recycled during the Cretaceous to Palaeogene magmatism in south‐eastern Korea, whereas the Palaeoarchaean to Palaeoproterozoic crust provided major source material for the Triassic to Jurassic granitoids in central Korea.  相似文献